Long-term survival in sporadic and familial medullary thyroid carcinoma with special reference to clinical characteristics as prognostic factors. The Swedish MTC Study Group.

All the 249 patients with medullary thyroid carcinoma (MTC) diagnosed during a 23-year period in Sweden were followed up completely for 4-27 years. The overall relative survival was 79.9% at 5 years after diagnosis and 68.6% at 10 years. After 5 years of follow-up, the relative survival rate was 5 percentage points higher in females than in males; 30 percentage points higher in patients aged less than 40 than in those 60-69 years at diagnosis; 24 percentage points higher in patients with familial disease detected at screening than in those with sporadic MTC; 20, 26 and 48 percentage points lower in patients with stage II, III, and IV, respectively, than in those with stage I; and almost 30 percentage points lower in the group of patients with a large tumor (greater than 3 cm) than in the group with a small one (less than 1 cm). In multivariate proportional hazards analyses of all these important determinants of outcome, the prognostic information provided by age and stage was still significant when several morphologic characteristics were taken into account (nuclear DNA content, calcitonin immunoreactivity, amyloid content, argyrophil reaction and state of the tumor capsule).